Disposable diaper with improved liner material

ABSTRACT

A disposable diaper having a conventional central pad of absorbent material, a conventional layer of fluid impervious material disposed on one side of the central pad and extending around the edges thereof, and an improved liner material disposed on the other side of the central pad and joined to the fluid impervious material around the periphery of the pad. The improved liner material comprises a high-loft, nonwoven fabric having a discontinuous backing layer of flexible adhesive, and including a multiplicity of hydrophobic fibers individually looped outwardly away from the backing layer with the ends of each loop embedded in the backing layer.

United States Patent 51 3,665,921

Stnmpf 1 54] DISPOSABLE DIAPER WITH 3,214,323 10/1965 Russell et al...128/290 w IMPROVED LINER MATERIAL 3,295,526 l/l967 Sabee ..128/2873,367,333 2/1968 Scheier.. 128/284 1 Invenmfl Robe" Stumpf, Appleton,W19 3,520,303 7/1970 Endres 128/287 [73] Assignee: Kimberly-ClarkCorporation, Neenah,

Wis Primary Exammer-Charles F. Rosenbaum Attorney-Wolfe, Hubbard,Leydig, Voit & Osann, Ltd. [22] Filed: Nov. 19, 1969 211 Appl. No.:877,968 [57] A disposable diaper having a conventional central pad ofabsorbent material, a conventional layer of fluid impervious..128/28Z,6if6i material disposed on one side of the central p andextending i l h U around the edges thereof, and an improved linermaterial [58] F e d of 128/284 161/148 disposed on the other side of thecentral pad and joined to the fluid impervious material around theperiphery of the pad. [56] References cued The improved liner materialcomprises a high-loft, nonwoven UNITED STATES PATENTS fabric having adiscontinuous backing layer of flexible adhesive, and including amultiplicity of hydrophobic fibers in- 2,705,498 4/ 1955 Johnson 128/290w dividually looped outwardly away from the backing layer with 2,788,0034/1957 Morin..." 3,085,309 4/1963 Olson 3,196,874 7/1965 Hrubecl y..l28/287 the ends of each loop embedded in the backing layer.

10 Claims, 13 Drawing Figures I II'IIA Patented May 30, 1972 3Sheets-Sheet 1 Patented May 30, 1972 3 Sheets-Sheet 2 a; \QLPH. WW Mm ZII II l I Patented May 30, 1972 3 Sheets-Sheet 3 DISPOSABLE DIAPER WITHIMPROVED LINER MATERIAL The present invention relates generally todisposable diapers and, more particularly, to a disposable diaper havingan improved liner material.

It is a primary object of the present invention to provide a disposablediaper having an improved liner material which provides goodcharacteristics for absorbing body liquids and transmitting the same toan inner core of absorbent material, and yet spaces the inner core ofabsorbent material away from the infants skin so that the liquidsretained in the absorbent core do not remain in contact with the skin.

A more specific object of the invention is to provide an improveddisposable diaper of the foregoing type which is soft and comfortable tothe infant wearing the diaper.

Another specific object of the invention is to provide such an improveddisposable diaper which minimizes retention of body liquids in the linermaterial, thereby minimizing rash and skin irritation problems.

It is another object of the invention to provide an improved disposablediaper of the type described above which provides extremely rapidabsorption of body liquids, combined with good liquid retentioncharacteristics.

A still further object of the invention is to provide such an improveddisposable diaper having a liner which is abrasion resistant so that itdoes not break down in use, and which does not lint onto the infantsskin.

Other objects and advantages of the invention will be apparent from thedetailed description taken in connection with .the accompanyingdrawings, in which:

FIG. 1 is a perspective view of a disposable diaper embodying theinvention, with the diaper in its folded, condition;

FIG. 2 is an enlarged perspective view of the diaper of FIG.

1 in its unfolded condition with fragments broken away to reveal theinternal structure; FIG. 3 is an enlarged section taken along line 3-3in FIG. FIG. 4 is a schematic side elevation of one form of apparatuswhich may be used to produce the improved liner material included in thediaper of FIGS. 1 and 2;

FIG. 5 is a fragmentary plan view somewhat simplified and exaggeratedfor the sake of clarity of illustration, of an illustrative web of basematerial prepared by the apparatus of FIG. 4 with portions of thematerial broken away to expose the various layers;

FIG. 6 is a fragmentary plan view of the liner material employed in thediaper of FIGS. 1 and 2, with portions broken away to expose the variouslayers;

FIG. 7 is an enlarged, simplified and somewhat exaggerated section takenalong section line 7-7 in FIG. 6;

FIG. 8 is an enlarged, simplified and somewhat exaggerated section takenalong line 8-8 in FIG. 6;

FIG. 9 is an enlarged schematic detail in side elevation of the formingdrum and gathering blade of the apparatus shown in FIG. 4;

FIG. 10 is a further enlarged schematic side elevation illus- I tratingin somewhat idealized fashion the sequence of gathering and looping ofindividual fibers;

FIG. 11 is an enlarged schematic fragmentary view taken along the line11-41 of FIG. 10 showing a fragment of the fiber web and adhesivepattern with illustrative fibers attached to the adhesive;

FIG. 12 is a simplified schematic view taken along the line 12-12 ofstill another sequence as shown in FIG. 10; and

FIG. 13 is an enlarged schematic bottom view showing the sequence of thepartial consolidation or closing of the open adhesive pattern to form adiscontinuous adhesive backing.

While the invention will be described in connection with certainpreferred embodiments, it will be understood that it is not intended tolimit the invention to these particular embodiments. On the contrary, isis intended to cover all alternative, modifications, and equivalentarrangements asmay be included within the spirit and scope of theinvention.

In disposable diaper construction, it is desirable to have an absorbentstructure which (I) immediately accepts body liquids, (2) rapidlytransports the liquids away from the discharge source, and (3)effectively contains the liquids within the confines of the diaper, allwhile the inside surface of the diaper is maintained relatively dry. Inaddition, the absorbed liquids should not be allowed to run over theinside surface of the diaper, or soak through the bottom of the diaper,especially if the absorbtive capacity of the diaper has not beenreached.

Turning now to the drawings, and referring first to FIGS. 1 and 2, thereis shown a disposable diaper 10 having a main absorbent material, afluid impervious outer sheet 12, and a fluid pervious liner 13 on theinside surface. In FIG. I, the diaper is illustrated as partially openedand ready for application to an infant, but it will be understood thatas packaged the diaper is flat folded with symmetrical half portionscontiguously engaged to minimize package volume. The illustrative diaperis formed by suitable infolding of a single blank along fold lines ofpatterned configuration as described in more detail in US. Pat. No.3,196,874.

The absorbent core 1 1 may be of varying construction, such as multiplesheets of creped cellulose wadding 14. Alternatively, the core 11 maycomprise a layer of cellulosic fluff or any other material ofi'eringsuitable fluid absorbent characteristics, it being the function of thecore 11 to provide substantial softness and bulk in addition to itsprimary function as the major fluid absorbent element.

Because of the fluid impervious outer sheet 12, the illustrative diapereliminates the need for a separate protective garment such as rubberpants or the like. The sheet 12 may be polyethylene sheet stock or thelike which offers the desirable characteristics of flexibility andsoftness while serving its primary function as a fluid imperviousenvelope for the associated diaper elements. The sheet 12 extendscoextensively of the core 11 and the margins thereof preferably enclosethe marginal areas of the core 11 with the sheet 12 being heat sealed orotherwise bonded along areas shown at 15 to the underside of theoverlying liner sheet 13, thereby forming a unitary assembly defining anenvelope-like enclosure for the core 11.

In accordance with the present invention, the disposable diaper isprovided with an improved liner material comprising a high-loft,nonwoven fabric, having a discontinuous backing layer of flexibleadhesive disposed adjacent the central pad, and a multiplicity of fibersindividually looped outwardly from said backing layer with the ends ofeach loop embedded in the backing layer. Thus, in the illustrativeembodiment, the liner material 13 is a high-loft, nonwoven materialpreferably prepared by the method and apparatus illustrated in FIG. 4.This apparatus includes a web forming section 20 and an adhesivecompacting and fiber looping section 30. The web forming section 20 isgenerally similar to the apparatus disclosed in copending applicationsSer. No. 498,929 and Ser. No. 553,483.

Multiple slivers 21 of heat-settable textile fibers are drawn from theirrespective supply cans (not shown) into a draw frame 22 which comprisesa series of pairs of grooved rolls 23, the rolls of each pair beingdriven by appropriate gearing well known in the art, at a peripheralrate of speed slightly faster than the rate of operation of thepreceding pair. As the juxtaposed slivers pass through draw frame 22,the individual fibers are drafted and spread out to form a flat striatedweb of substantially alined fibers as shown at 24. Web 24 is maintainedon a supporting conveyor sheet 25 on the surface of which a patternedadhesive has been previously applied.

In the illustrative arrangement the conveyor sheet 15 comprises anendless conveyor belt treated on at least its upper surface with arelease agent, e.g., a woven glass fiber with a surface coating oftetrafluoroethylene resin. Other release coatings are well known, andcomprise such materials as silicone, fatty acid metal complexes, certainacrylic polymers, and the like. Heat resistant films or thin metalsheets treated with release agents may also be used as the carriersheet.

Prior to the time the web 24 is picked up by the belt 25, the latter hasimprinted on its release-treated surface a pattern of flexiblethermoplastic adhesive such as is shown at 26 in FIG. 5. It isunderstood that the adhesive is actually on the underside of belt 25which becomes the upper surface after passing around roll 27 whereby theadhesive pattern 26 directly contacts the fiber web 24. The pattern isshown as being visible in FIG. only for illustrative purposes.

The belt 25 is fed around roll 27 at a speed slightly in excess of thedelivery speed of the final pair of rolls 23 in order to maintain web 24under slight tension whereby the individual highly-drafted fibers areretained in their alined and tensioned condition. Drive rolls 28, 29 arerotated to drive belt 25 at a speed sufficient to maintain the propertension on the web 24.

In the method shown for applying adhesive, the belt 25 is fed through anip formed between the printing roll 30 and a back-up roll 31 maintainedin very light pressure engagement therewith. The surface of printingroll 30 is provided with an intaglio pattern which picks up adhesive 32from dip pan 33. Part of the adhesive thus picked up is removed by adoctor blade 34 leaving only the intaglio patterned surface filled. Theprinting roll 30 then transfers this metered amount of adhesive in apreselected pattern to the underside of release coated belt 25. Thepattern shown in FIG. 5 is in the form of an open diamond pattern ofadhesive.

Since the surface of belt 25 is treated with a release coating, theadhesive remains substantially on the surface with no penetrationtherein and is preferably in a somewhat tacky condition. The printedbelt is drawn from the printing nip around roll 27 positioned closelyadjacent the output end of draw frame 22, and, as stated above, at aspeed slightly in excess of the delivery speed of the last two rolls inthe draw frame. The web 24 emerging from the draw frame 22 is depositedon the tacky adhesive on belt 25 and held in tensioned engagementtherewith by the adhesive and the above-mentioned speed differential.This continuous tension prevents the fibers in the web from losing theirhighly-drafted and alined condition.

If desired, additional alined and highly drafted fibers may be added tothe web 24 on the adhesively printed belt 25. For this purpose, a seconddraw frame 35 similar to the draw frame 22 is provided to drawadditional slivers 36 of fibers from their supply cans (not shown) and,after drafting and alining them, deposit the fibers on the moving web 24carried by the belt 25. In such cases, the amount of adhesive printed onthe belt 25 is increased so that some penetrations of the adhesivepattern reach the fibers from the second draw frame 35, and togetherwith the speed differential of the belt 25 relative to the last pair ofrolls in the draw frame 35, maintains these fibers under slight tensionwhereby they also maintain their highly-drafted and alined condition.

An example of the web 24 formed by the apparatus is shown in FIG. 5. Aspreviously mentioned, a series of parallel and diagonally disposed linesof adhesive are printed in crisscross fashion on the belt to formpattern 26 of adhesive having substantial open spaces in theconfiguration of diamonds. It should be appreciated, of course, thatFIG. 5 is only intended to be illustrative and, while the linesrepresenting the fibers for both components 24a and 24b are spaced apartfor clarity, in practice the highly-drafted fibers of both componentsare very close to one another. Following deposit of web components 24aand 24b on the adhesive printed belt 25, the belt is drawn around aheated drum 39 where fusing and curing of the adhesive is substantiallycompleted while the web 24 is maintained in firm contact therewith tobond the individual fibers. To insure effective heating and fusing ofthe adhesive, it is desirable that travel of the combined belt and webbe around a substantial portion of the drum 39. In the illustratedembodiment, a fly roll 39a is disposed to provide wrap for the combinedbelt and web as they travel around the drum 39 to insure completeembedment of the fibers in the adhesive. The fibers of the web 24 arethus bonded together while retaining their highly-drafted andsubstantially alined condition in the particular pattern in which theywere deposited on the open pattern of adhesive 26 printed on the belt25. After leaving the fly roll 39a, the combined web 24 and belt 25 arepreferably passed over the drive roll 29 which also serves as a coolingdrum, to set the adhesive. The bonded web 24 is stripped from therelease coated surface of the belt 25 by the guide roll 41 as the webleaves the cooling roll 29.

In general, any of the various known adhesives may be employed. Itshould, however, be appreciated that the particular adhesive used isdependent upon the characteristics of the flexible heat-settable fibrousweb that is being employed, i.e. the adhesive should be reactivatableand softened in the heat-setting range of the particular fibrousmaterial being used. In addition, the adhesives should also: beapplicable to the base web 24 by procedures which will not disarrangethe fibrous structure of the web; be reactivatable in the subsequentadhesive gathering and partial consolidation stage of the process; andform a flexible discontinuous backing layer for the finished fabric andshould strongly bond the fiber loops in place.

While various well-known adhesives may be employed in the foregoingprocess, advantages reside in the use of plastisols, which are colloidaldispersions of synthetic resins in a suitable organic ester plasticizer,and which under the influence of heat provide good binding power whileremaining soft and flexible. While many adhesives of this type areknown, those found particularly useful for incorporation in the productof this invention include vinyl chloride polymers, and copolymers ofvinyl chloride with other vinyl resins, plasticized by organicphthlates, sebacates, or adipates. These provide a fast curing plastisoladhesive characterized by relatively low viscosity, low migrationtendencies, and minimum volatility. Such adhesives remain soft andflexible after curing, and can be reactivated by subsequent heating.

It has been found that other adhesive systems may be employed in theprocess, such as organisols, utilizing resins such as the vinyl chloridepolymers, and copolymers. Furthermore, other adhesives may be employedprovided that they satisfy specified characteristics in the base webproduced in the web forming stage, and in the finished fabric producedin the adhesive compacting and fiber looping stage. For example,emulsions of thermoplastic resins such as acrylics and rubber-likecompounds illustratively ABS have the requisite properties to serve asthe bonding adhesive for the web 24.

The base material made as heretofore described and comprising a web ofhighly drafted, heat-settable, fibers embedded in an open adhesivepattern, is then fed into the adhesive consolidating and fiber loopingsection 40 of the system shown in FIG. 4. The web 24 while still undertension is fed around an idler roll 42 and onto the surface of a heatedforming drum 47. The forming drum is maintained at a temperature whichwill soften the adhesive to a tacky state so that it adheres to the drumsurface while also heating the fibers sufficiently to bring them intotheir heat-setting range. In its preferred embodiment the drum 47 ismade of metal with a highly polished chromium plated surface which isinternally heated. Also, the web 24 is desirably arranged to travel asubstantial distance around the drum 47 (i.e. have a relatively highdegree of wrap) with the open pattern of adhesive 26 in contact with theheated drum surface to provide adequate residence time.

As the web 24 is fed onto the drum 47 the heat from the drum surfaceheats the fibers to their heat-setting temperature range and reactivatesand softens the adhesive printed on the underside of the web, causing itto become tacky and to adhere slightly to the drum surface therebymaintaining the web under constant tension. The drum temperature shouldbe maintained below the melting point of the adhesive to preventdispersion of the adhesive into the fibers of the web and to minimizebonding of the adhesive lines as will hereinafter be described ingreater detail. The web of fibers and softened adhesive is reformed bythe cooperative action of the drum 47 and a gathering blade 48 having aflat edge 49. The blade edge 49 operates to consolidate the openadhesive pattern 26 into a backing layer of adhesive whilesimultaneously looping the fibers of the web outwardly from the openspaces in the The present invention may be more completely understoodfrom the following examples, which are illustrative of the invention butare not intended as limiting the scope of the invention. The method andapparatus of FIG. 4 was employed for forming the liner material for theproducts described in the ensuing examples. The adhesive used was aplastisol formulation including, by weight: Geon l35 polyvinyl chlorideresin (manufactured by B. F. Goodrich, Akon, Ohio), about 60 parts per100 parts resin of Gi -261" diotyl phthalate plasticizer (B. F.Goodrich), about 2.5 parts per 100 parts resin of CAB-O-SIL" pyrogenicsilica (Cabot Corporation, Boston, Mass.) and a sufficient amount ofmineral spirits to bring the viscosity into the desired range (generallyfrom about 3 to 5 percent by weight, based on the total weight of theother components for a viscosity range of 3,500 4,000 cps). Theviscosities were measured with a Brookfield viscometer using a No. 4spindle and operating at rpm. The polyester used in the Examples wasFortrel Type 400 staple fibers, commercially available from CelaneseFibers Marketing Company, Charlotte, NC. The approximate tenacity ofthese fibers is 4.8 g.p.d. with elongation at break falling in the 45-55percent range. Other physical properties include: loop tenacity (g.p.d.)4.4, initial modulus (g.p.d.) 40-45, yield stress (g.p.d.) 1.0, yieldstrain 3.7 percent, specific gravity 1.38 and melting point 500 F.

EXAMPLE I The base web was made from polyester fiber having a denier ofabout 2.25 and an average fiber length of 2% inches. The polyvinylchloride plastisol, having a viscosity of from 3,700 to 4,000centipoises, was applied in diagonal lines one-fourth inch apart in bothdirections to form a diamond pattern. Rotogravure printing was employedand the intaglio roll had adhesive cells or lines 0.006 inch deep and0.028 inch wide. The weight of the base web was about 12.8 grams/sq.yd., with equal weights of fiber and adhesive being included.

The preheat drum 39 in the first stage of fonning the web was maintainedat about 300 F. and operated at a surface speed of '65 ft./min. The baseweb 24 was thus carried to the heating drum 37 at a surface speed of 65ft./min.

The gathering blade 48 was positioned at an angle A of 54 and maintainedagainst the drumwith a pressure of 27 p.s.i. The drum (9 inches indiameter) was internally heated and maintained at a temperature of about260 F.

The take-away speed was 8 ft./min. to provide a take-away ratio (i.e.surface speed around drum/take-away speed) of 8.125. The resultantproduct weighed about 104 grams/yd. This material was then openedbetween two nips, the first traveling one-sixth the speed of the second,and then allowed to relax. The final product, which weighed 32 grams/yd.was used as a diaper liner in disposable diapers made with the samematerials used in the present commercial disposable diapers known asKimbies (except for the liner material)v Subjective tests conducted withthese diapers yielded relatively consistent favorable comments on thesoftness and strength of the liner material and particularly on theimproved dryness of the skin of the infants on whom the diapers wereused.

EXAMPLE II Example I was repeated, except that the blade angle A wasvaried between 17 and 74 (17, 34, 37, 45, 54, and 74 being specificallyused), and the weight of the base web was about 13 grams/sq. yd., withequal weights of fiber and adhesive being included.

Elastic nonwoven material capable of being stretched up to about twiceits opened machine direction length with a recoverability of from 80 to100 percent was obtained when the blade angle A was between about 20 and54, (i.e. optimum stretch was not obtained with angles of 17 and 74).

EXAMPLE III The base web was made from polyester fiber having a denierof 2.25 and an average fiber length of 3 inches. The polyvinyl chlorideplastisol having a viscosity of about 3.800 centipoises was applied indiagonal lines one-fourth inch apart in both directions to form adiamond pattern. The intaglio roll used was the same as in Example I.The base web, which weighed 12.5 grams/yd, was cured on the preheat drum39 at 290 F at a surface speed of 58 fpm. It was then carried to theheating drum 37. The gathering blade 48 was positioned at an angle A of74 and maintained with a pressure of 27 p.s.i. The drum 37 was heated toa temperature of 270 F. The take away was run at 40 ft./min. (i.e. 1.45to 1 ratio). The resultant product weighed 18.1 grams/yd.

As has been thus seen from the preceding Examples, elastic, high-loftnonwoven diaper liners can be made in accordance with the presentinvention by carefully controlling certain process parameters.Initially, the edge angle A must be kept within certain critical ranges,depending upon the other parameters involved such as, for example, typeof adhesive pattern and fiber stiffness. Thus, while angles of fromabout 20 to about 120 could be employed, the critical range narrows whenfiber stiffness, type of adhesive and adhesive pat tern are known. Forexample, with a 2.25 denier polyester, a polyvinyl chloride plastisoland a diamond pattern, a range of from about 20 to 54 should beemployed.

The take-away speed of the fabric from the blade edge is also important.With blade 48 having an edge angle A within the preferred range, andassuming the take-away surface is cooled to substantially an ambienttemperature, e.g. 75 F. to F., the normal ratio of the surface speed ofthe heating drum 37 to the take-away speed should be maintained in therange of from about 5:1 to about 10:1, with a ratio of 7 to 8:1 beingpreferred. By increasing the ratio above 10:1 by slowing down the fabrictake-away speed, more adhesive consolidation has been obtained and themass of the fiber loops is made somewhat more dense, so that a fabricwith a higher weight has been produced; but the adhesive lines becomemore strongly bonded together so subsequent drawing cannot open theadhesive. By increasing the fabric take-away speed, such that the fabricis not allowed to gather at the blade edge, the fabric will be drawn orextended while the adhesive layer is still in a plastic condition,thereby opening the adhesive layer, but not allowing sufficientresidence time for the fibers to become as well heat set. Such webswhile not as elastic still retain the properties of rapid liquid passageand no strikeback.

Further parameters that affect adhesive consolidation, fiber looping atthe blade edge and the stretchability and elasticity characteristics ofthe elastic nonwoven fabric are the adhesive pattern applied to thefibers in the formation of the base web, the adhesive weight as apercentage of the weight of the web, and the area of the web covered bythe adhesive pattern. The adhesive was applied in the preparation ofExamples l and II in the form of diagonal lines, criss-crossed, toprovide an open diamond pattern with the size of the opening in thediamond in the machine direction less than the lengths of the fibersused for the base webs. Thus, where Fortrel" T-400 polyester was used,with fiber lengths from 2 75 inches to 3 inches, a A inch diamondpattern applying adhesive to 20 to 25 percent of the total web surfacewas found effective. The transverse adhesive lines, when consolidated bythe action of the gathering blade, are moved into proximity or abutmentwith each other but are only minimally bonded together. Thus, when theclosed form of the elastic nonwoven is opened, the original pattern willreappear but will be foreshortened (i.e. the machine direction distanceof the pattern will be less).

In the application of the adhesive to the base web, it has been observedthat by increasing the adhesive viscosity a sharp, distinct printedpattern will be obtained such that the fibers are securely attached tothe adhesive at distinct spaced points and are not embedded in adhesivethroughout their length. It is desired to have spaced points of fiberadhesive attachment so that the fiber loops will be distinctly andseparately formed at the gathering blade so as to extend outwardly fromthe bonding adhesive layer. Fiber sizes over the entire prepared rangeof 1.5 to 3.0 denier have been successfully original adhesive pattern.The reformed and consolidated material 50 then leaves the blade edge 49and onto a flat takeoff surface 51 and a discharge conveyor 52.

The speed at which the material leaves the gathering blade is closelycoordinated with the surface speed of the drum to heat set the fibers intheir looped positions while rendering the adhesive non-tacky so theconsolidation of the adhesive will only be partial and the bonding oftransverse lines of adhesive minimized. To this end and as shown in FIG.4, this may be accomplished by maintaining the take-off surface 51 atthe ambient temperature or slightly higher by directing an air spray 53at the bottom surface of take-off member 51. While this providesadequate cooling to carry out the objectives of the conditioning step,other means such as a water spray or a refrigerated fluid could beemployed to provide a lower temperature if desired. Indeed, as long asthe fluid is inert as regards the fibers and adhesives, application maybe directly on the partially consolidated and reformed web. Thetake-away speed should then be set so that, at the temperature of thetake-away surface, the fibers will be heat set and yet the bonding ofmerging lines of adhesive will be minimized. In this connection, itshould be noted that the adhesive should be maintained below its meltingpoint to minimize the flowing together of the merging adhesive lineswhich would provide undesired bonds.

Turning now to FIGS. through 13, the method of making the elastic,high-loft, nonwoven fabric 50 will be explained in greater detail inconnection with an illustrative sequence of the gathering and looping ofsingle fibers of the web 24 (FIGS. 10 through 12) and the partialconsolidation of the illustrative diamond adhesive pattern 26 (FIG. 13).As seen in FIG. 11, the fiber has a portion which extends across theopen space of the diamond pattern of adhesive 26 from point A to B whereit is embedded in the adhesive. Referring to FIG. 10, the series ofviews in this Figure illustrates how the portion P of the fiber isformed into a loop; when point A being carried around the heated drum 47impinges against the gathering blade edge 49, its forward motion ishalted and it is scraped along the surface of the drum. Point Bcontinues to advance with the drum surface since due to its softened andtacky condition it adheres to the smooth drum surface.

As point B advances relative to point A, the portion P of the fiberbetween points A and B is caused to bow outwardly from the drum surface.Finally, point B overtakes point A and these points of adhesive arebrought close together without being consolidated as seen in FIG. 12. Inthe meantime, fiber portion P has been looped outwardly from the drumsurface. While this is occurring, of course, additional adhesive pointsC-D. etc., travelling around the drum 47 impinge against the gatheringblade edge 49 causing a consolidation of these adhesive points andlooping of their intermediate fiber portions P as is also indicated inFIG. 12. This occurs simultaneously at all points across the web at theblade edge producing a backing layer of adhesive from which extends themultiplicity of loops formed by the fibers of the base web. The layer ofadhesive is carried away from the blade edge along the take-off surface51 and provides a backing layer for the outwardly looped fibers, thusproducing the fabric 50.

Also, not only does each fiber portion P loop outwardly from the drumsurface but as the loop is formed it may twist or turn. The degree ofloop twisting, and indeed, whether any twisting occurs, is dependentupon such factors as the degree of adhesive consolidation, fiberstiffness, blade angle (as hereinafter defined) and relative uniformityof loop size. In a particular situation, the formed loops may turnthrough an angle ofup to 180.

FIG. 13 illustrates the partial consolidation that is desired when theopen adhesive pattern is the exemplary diamond pattern. Thus,considering a single diamond S, each of the four comers T represents thecrossing point of two intersecting lines of adhesive U and V. At everycorner T then, as the adhesive is scraped along the surface of the drum,the crossing adhesive lines U and V are brought close and closertogether.

The points closest to the comers T merge first because of the shorterdistance of separation. Accordingly, point P on line U will merge withpoint P on line V before point P will meet point P Similarly, on theother side of the comer, the closer set of points (e.g. P-, and P,;)will merge before points I and P To provide the desired liner materialfor use in the present invention, the take-away speed is maintained at arate such that the adhesive diamonds are not completely consolidated butare collapsed into flat hexagonal shapes in which the crossing points ofadhesive have been transformed by partial consolidation of the adhesiveinto lines that form the sides of the highly elongated hexagons, asshown in FIG. 13. The closed, compact form of the nonwoven fabric may bestretched apart to break the bonds of minimal strength (i.e. the bondsthat will break before adhesive rupture or other degradation of theproduct). The fabric is then allowed to relax to come to an equilibriumstate in its drawn or open position.

The drawing may be accomplished by hand and can be achieved by pullingthe fabric apart (i.e. -along the machine direction). As shown in FIG.4, the fabric exit end of the conveyor 52 may be provided with a roll 54to form a nip and a pair of rolls 55, also forming a nip. Drawing isaccomplished by driving the rollers 55 at a higher speed.

With respect to the loops, it should be appreciated that the heights ofthe fiber loops throughout the fabric vary according to the spacingbetween the points of attachment of each fiber to the open adhesivepattern in the base web. Referring to FIGS. 8, 11 and 12, it will beseen, for example, that the loop formed by the fiber portion P betweenthe points of adhesive attachment CD will have a lower height than theloop formed by the longer fiber portion P between the points A,B. Thisresults in a dense fabric with the lower loops supporting and fillingaround the higher loops and the top surface of the fabric being formedby the tops of the higher loops.

In accordance with an important aspect of this invention, the base webused to form the high loft liner material comprises fine denier, heatsettable, hydrophobic fibers. The fine denier of the fibers providesdesired softness to the fabric, the heat settable characteristicimproves the loft or bulk stability of the fabric, and the hydrophobicnature of the fibers provides a liner material which is substantiallynon-wetting while at the same time readily passing body fluidstherethrough. The denier of the fibers is preferably in the range offrom about 1 .5 to about 3.0 denier. Suitable hydrophobic properties areprovided by fibers of polyester, polypropylene, or acrylic. Byheat-settable it is meant that the material will maintain the loopedconfiguration into which it has been formed in accordance with thepresent invention, regardless of whether the stability of the loop maybe attributed to what is technically considered heat setting or whetherthe setting is the result of some other phenomena. Representativeexamples of suitable materials include any of the commercially availableacrylic fibers such as, for example, Creslon" (American Cyanamid,Stamford, Conn.) and Orlon (E.l. duPont de Nemours and Company,Wilmington, Del.) and olefins such as polypropylene. If desired, a blendof fibers may be used in which only a portion of the fibers are heatsettable. This will not, of course, provide the optimum elasticproperties. Moreover, not only highly drafted webs and carded webs ofstaple length fibers may be used for the base but also gameted and airlaid webs of such fibers as well as directly laid alined webs ofmonofilament. It has been noted, however, that when webs such as cardedwebs are used for the base web in which an important proportion of thefibers are randomly oriented, those fibers not alined with the machinedirection ap ear to interfere with the loop production by the gatheringblade and the ultimate stretch characteristics. The most regularformation of loops and optimum elastic and stretch in the formed fabrichas been produced with those base webs having the highest proportion offibers alined with the machine direction as, for example, the highlydrafted webs made with the apparatus illustrated in FIG. 4.

utilized in the base web with a inch diamond pattern of adhesive. Withthe light weight webs of polyester used in the Examples, the ratio offiber to adhesive was approximately l:l. It has been found that thedegree of adhesive-fiber attachment in the base web is afiected when thefiber to adhesive ratio with such type fibers is increased above about2.5:1, so that the fiber loops do not form properly at the blade nor dothe fibers have sufficient attachment to the adhesive layer in thefinished fabric. n the other hand, increasing the relative amount ofadhesive in the base web tends to produce a thicker adhesive layer inthe finished material and more secure fiber attachment, but the adhesivelines tend to disperse so that the pattern becomes less open affectingthe height of the loops, which is undesirable. The fiber-adhesive ratiowill be different, however, for base webs of yarns and threads where itappears that less amounts of adhesive, relatively speaking, will provideadequate attachment of the loops to the adhesive backing layer. For thepurposes of the present invention, the aforementioned parameters are allpreferably selected to provide a final gathered web of about 25 to about40 grams/yd.

It is also recognized that to produce a material in accordance with theinvention, the elements should be sufficiently flexible to allow theloops to form under the action of the adhesive consolidating andgathering blade. Thus, neither stiff strands which do not loop under theaction of the gathering blade, nor multiple strand yarns in which thelay of the strands opposes the tendency of the loops being formed toassume their equilibrium position under the action of the blade, willsatisfactorily serve as elements of the base web when it is desired toproduce a fabric fully in accordance with the invention.

As shown in FIG. 4, the fabric is carried along the take-away surface 51by the action of the conveyor 62. Since the adhesive backing is hot andtacky as the fabric flows onto the takeaway surface 51 which ismaintained substantially at ambient temperatures, that'surface may betreated with a nonstick or release coating to insure that the fabric maybe drawn smoothly along the surface.

To cool the belt of the conveyor 52 and prevent it from becomingoverheated from the hot adhesive back of the fabric 50, streams of airmay be blown against the underside of the belt from suitably placed airnozzles 60. This will also serve to cool the fabric 50, although it maybe necessary or desirable to pass the fabric through a cooling stationor zone to cool the adhesive and thermoplastic fibers clearly belowtheir softening temperatures or to eliminate tackiness of the adhesive.

The improved liner material provided by this invention provides rapidpassage of urine and other body liquids into the absorbent corematerial, and yet the absorbed liquid does not strike back through theliner material. In fact, the liner material is essentially non-wettableby the body liquids. It is believed that these results are due to theunique combination of characteristics of the liner material,particularly its bulk or loft and its hydrophobic nature.

l claim as my invention:

1. An improved disposable diaper comprising the combination of a centralpad of absorbent material, a layer of fluid impervious material disposedon one side of said central pad and extending around the edges thereof,and an elastic liner disposed on the other side of said central pad andjoined to said fluid impervious material around the periphery of saidcentral pad, said liner comprising an elastic high-loft, nonwoven fabrichaving a discontinuous backing layer of flexible adhesive disposedadjacent to said central pad, and a multiplicity of heat settablehydrophobic fibers individually looped outwardly from said backing layerand heat set in the looped form with the ends of each loop embedded insaid backing layer.

2. An improved disposable diaper as set forth in claim 1, wherein saidliner fabric has a weight of from about 25 to about 40 grams per squareyard.

3. An improved disposable diaper as set forth in claim 1, wherein saidfibers in said liner fabric have a denier of from about 1.5 to about3.0.

4. An improved disposable diaper as set forth in claim 1,

wherein said backing layer of said liner fabric comprises a series ofinterconnected hexagons of adhesive.

5. An improved disposable diaper as set forth in claim I, wherein saidfiber loops in said liner fabric lie in planes extending in the crossdirection of the fabric.

6. An improved disposable diaper as defined in claim 1 wherein thelength of the fibers forming said loops varies regularly in the crossdirection throughout the high-loft, nonwoven fabric liner, the embeddedends of said loops laying essentially in the same plane.

7. An improved disposable diaper as defined in claim 1 wherein thefabric is formed of a blend of fibers in which at least some of saidfibers are heat settable and heat-set in the looped configuration toprovide a stretchable and elastic liner.

8. An improved disposable diaper as defined in claim 1 whereinsubstantially all of said fibers loop outwardly and span the open spacesin the discontinuous backing layer to provide a stretchable liner, saidopen spaces facilitating the passing of fluids through said liner tosaid central pad of absorbent material.

9. An improved disposable diaper comprising the combination of a centralpad of absorbent material, a layer of fluid impervious material disposedon one side of said central pad and extending around the edges thereof,and an elastic liner disposed on the other side of said central pad andjoined to said fluid impervious material around the periphery of saidcentral pad, said liner comprising a high-loft, non-woven fabric havinga discontinuous backing layer formed by an open pattern of flexibleadhesive disposed adjacent to said central pad, and a multiplicity ofheat settable hydrophobic fibers which are individually looped outwardlyfrom said backing layer and heat set in the looped form with the ends ofeach loop embedded in said backing layer, said loops extending over thespaces in said open adhesive pattern forming said discontinuous backinglayer, said spaces providing apertures through which fluids may freelypass into said central pad of absorbent material.

10. In a disposable diaper comprising the combination of a central padof absorbent material, and a layer of fluid impervious material disposedon one side of said central pad and extending around the edges thereof,an improved liner disposed on the other side of said central pad andjoined to said fluid impervious material around the periphery of saidcentral pad, said liner comprising an elastic high-loft, nonwoven fabrichaving a discontinuous backing layer of flexible adhesive disposedadjacent to said central pad and a multiplicity of heat settablehydrophobic fibers individually looped outwardly from said backing layerand heat set in the looped form with the ends of each loop embedded insaid backing layer, said backing layer having been formed by gatheringand thereafter partially reopening an open adhesive pattern upon which aflat web of generally longitudinally oriented heat settable hydrophobicfibers are bonded, said gathering being efiective to outwardly loop saidfibers from said discontinuous backing layer of flexible adhesive.

2. An improved disposable diaper as set forth in claim 1, wherein saidliner fabric has a weight of from about 25 to about 40 grams per squareyard.
 3. An improved disposable diaper as set forth in claim 1, whereinsaid fibers in said liner fabric have a denier of from about 1.5 toabout 3.0.
 4. An improved disposable diaper as set forth in claim 1,wherein said backing layer of said liner fabric comprises a series ofinterconnected hexagons of adhesive.
 5. An improved disposable diaper asset forth in claim 1, wherein said fiber loops in said liner fabric liein planes extending in the cross direction of the fabric.
 6. An improveddisposable diaper as defined in claim 1 wherein the length of the fibersforming said loops varies regularly in the cross direction throughoutthe high-loft, nonwoven fabric liner, the embedded ends of said loopslaying essentially in the same plane.
 7. An improved disposable diaperas defined in claim 1 wherein the fabric is formed of a blend of fibersin which at least some of said fibers are heat settable and heat-set inthe looped configuration to provide a stretchable and elastic liner. 8.An improved disposable diaper as defined in claim 1 whereinsubstantially all of said fibers loop outwardly and span the open spacesin the discontinuous backing layer to provide a stretchable liner, saidopen spaces facilitating the passing of fluids through said liner tosaid central pad of absorbent material.
 9. An improved disposable diapercomprising the combination of a central pad of absorbent material, alayer of fluid impervious material disposed on one side of said centralpad and extending around the edges thereof, and an elastic linerdisposed on the other side of said central pad and joined to said fluidimpervious material around the periphery of said central pad, said linercomprising a high-loft, non-woven fabric having a discontinuous backinglayer formed by an open pattern of flexible adhesive disposed adjacentto said central pad, and a multiplicity of heat settable hydrophobicfibers which are individually looped outwardly from said backing layerand heat set in the looped form with the ends of each loop embedded insaid backing layer, said loops extending over the spaces in said openadhesive pattern forming said discontinuous backing layer, said spacesproviding apertures through which fluids may freely pass into saidcentral pad of absorbent material.
 10. In a disposable diaper comprisingthe combination of a central pad of absorbent material, and a layer offluid impervious material disposed on one side of said central pad andextending around the edges thereof, an improved liner disposed on theother side of said central pad and joined to said fluid imperviousmaterial around the periphery of said central pad, said liner comprisingan elastic high-loft, non-woven fabric having a discontinuous backinglayer of flexible adhesive disposed adjacent to said central pad and amultiplicity of heat settable hydrophobic fibers individually loopedoutwardly from said backing layer and heat set in the looped form withthe ends of each loop embedded in said backing layer, said backing layerhaving been formed by gathering and thereafter partially reopening anopen adhesive pattern upon which a flat web of generally longitudinallyoriented heat settable hydrophobic fibers are bonded, said gatheringbeing effective to outwardly loop said fibers from said discontinuouSbacking layer of flexible adhesive.